Polikarpov I-15, also known as “Seagull”, because of the distinctive shape of the upper wing, which was made according to the “gull” scheme.
In total, 3,313 I-15s were produced, not to mention 3,437 I-153 – an upgraded version of the I-15. The first flight was made in 1933 and entered service in 1934. The fighter was easy to fly, was exceptionally stable in flight, distinguished by its remarkable take-off and landing characteristics and a favorite among pilots.
The I-15 had a characteristic design of her time. The Soviet single-seat fighter had a cylindrical fuselage with a radial engine positioned in the front. Behind the engine was a a biplane wing assembly – the upper wing had an up-angled look. The gulled upper wing of the I-15 was unpopular with some pilots, as it was felt to restrict visibility, so Polikarpov’s design bureau produced a revised version, the I-15bis, with a longer span un-gulled upper wing.
Behind the wings was the position of the pilot, sitting in an exposed cockpit. His head and neck were protected from behind by the raised fuselage spine. In general, his line of sight was dominated by the front engine and biplane wings. The empennage was a vertical tail fin with horizontal planes. The undercarriage was two fixed single-wheeled main landing gear in the front and a small tail wheel. I-15 was 6.1m long, 2.2m high, an empty weight of 1 ton, and a maximum takeoff weight of 1.7 tons.
Polikarpov I-15 was equipped with a Shvetsov M-25 9-cylinder air-cooled radial piston engine, 700 horsepower capacity. The fighter could reach top speed of 367 km/h, cruise speed was 285 km/h, range was 510 km, and service ceiling was 9,800 m. Climb rate was 2,500 feet per minute.
Regarding weapons, the I-15 was equipped with four 7.62mm PV-1 machine guns. It could carry 100 kg of bombs. Additionally, 6 x RS-82 unguided high-explosive rockets ultimately figured into the strike fighter role of the I-15, making for a more valuable battlefield system.
Together with the Polikarpov I-16 monoplane, I-15 was one of the standard fighters of the Spanish Republicans during the Spanish Civil War, where it was called Chato.
Air battles in the skies of Spain demonstrated the superiority of the I-15 fighter over the main French fighters — the Italian Fiat CR.32 and the German Heinkel He-51-A-1. Here, in the sky over Spain, I-15 first met Me-109 fighters from the Condor Legion. At the same time, the Messerschmitt pilots used the tactics of surprise attack and quick exit, regardless of whether they succeeded in knocking down the Republican fighter.